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 A171260 Numbers n such that sigma(n) = 15*phi(n) (where sigma=A000203, phi=A000010). 5
 840, 11880, 12180, 25080, 32130, 67830, 79170, 172260, 282744, 312840, 363660, 569160, 596904, 634410, 696696, 843780, 846090, 959310, 996840, 1119690, 1201560, 1402440, 1542840, 1607340, 1929312, 2104440, 2247210, 2363790, 3309240, 3368040, 3883680 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Donovan Johnson, Table of n, a(n) for n = 1..1000 Kevin A. Broughan and Daniel Delbourgo, On the Ratio of the Sum of Divisors and Eulerâ€™s Totient Function I, Journal of Integer Sequences, Vol. 16 (2013), Article 13.8.8. Kevin A. Broughan and Qizhi Zhou, On the Ratio of the Sum of Divisors and Euler's Totient Function II, Journal of Integer Sequences, Vol. 17 (2014), Article 14.9.2. PROG (PARI) for(k=1, 3e6, sigma(k) - 15*eulerphi(k) | print1(k", ")); CROSSREFS Cf. A062699, A068391, A068390, A136547, A104900, A136540, A104901, A163667, A171256, A171257, A104902, A171258, A171259, A104903. Sequence in context: A276161 A135038 A215230 * A166758 A188781 A166764 Adjacent sequences:  A171257 A171258 A171259 * A171261 A171262 A171263 KEYWORD nonn AUTHOR Farideh Firoozbakht and M. F. Hasler, Mar 19 2010 STATUS approved

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Last modified February 22 19:59 EST 2019. Contains 320403 sequences. (Running on oeis4.)